PROSITE documentation PDOC51969
CBM39 (carbohydrate binding type-39) domain profile


The enzymic degradation of insoluble polysaccharides is one of the most important reactions on earth. Despite this, glycoside hydrolases attack such polysaccharides relatively inefficiently as their target glycosidic bonds are often inaccessible to the active site of the appropriate enzymes. In order to overcome these problems, many of the glycoside hydrolases that utilize insoluble substrates are modular, comprising catalytic modules appended to one or more non-catalytic CBMs (carbohydrate-binding modules). CBMs promote the association of the enzyme with the substrate [1].

βGRPs, also called Gram-negative bacteria binding proteins (GNBPs), make up a family of insect pathogen recognition receptors that bind to β-1,3-glucan, a structural component of fungal cell walls and bacterial surfaces. The protein-carbohydrate binding event triggers activation of serine protease cascades leading to the activation of the prophenoloxidase (proPO) pathway in the hemolymph and intracellular Toll signaling. The activated proPO pathway produces melanin that encapsulates pathogenic microorganisms, whereas the Toll pathway results in the expression of antimicrobial peptides and/or proteins. βGRPs consist of an N-terminal β-1,3-glucan-recognition domain (N-βGRP, also known as GNBP homologous domain) and a C-terminal glucanase-like domain, with the former reported to be responsible for the proPO cascade activation. N-βGRP binds to Curdlan, a linear water-insoluble β-1,3-glucan polysaccharide, and to laminarin, a water-soluble β-1,3-glucan polysaccharide containing β-1,6 branches. The N-βGRP domain is classified as a CBM39 [E1] and is sufficient for agglutination of microorganisms and activation of the proPO cascade [2,3,4,5].

The N-βGRP domain is comprised of 100 amino acid residues and has an immunoglobulin-like β-sandwich fold composed of two antiparallel β-sheets containing three and five β-strands (see <PDB:2KHA>) [2,3,4,5].

The profile we developed covers the entire CBM39 domain.

Last update:

April 2021 / First entry.


Technical section

PROSITE method (with tools and information) covered by this documentation:

CBM39, PS51969; CBM39 (carbohydrate binding type-39) domain profile  (MATRIX)


1AuthorsBoraston A.B. Bolam D.N. Gilbert H.J. Davies G.J.
TitleCarbohydrate-binding modules: fine-tuning polysaccharide recognition.
SourceBiochem. J. 382:769-781(2004).
PubMed ID15214846

2AuthorsTakahasi K. Ochiai M. Horiuchi M. Kumeta H. Ogura K. Ashida M. Inagaki F.
TitleSolution structure of the silkworm betaGRP/GNBP3 N-terminal domain reveals the mechanism for beta-1,3-glucan-specific recognition.
SourceProc. Natl. Acad. Sci. U. S. A. 106:11679-11684(2009).
PubMed ID19561300

3AuthorsMishima Y. Quintin J. Aimanianda V. Kellenberger C. Coste F. Clavaud C. Hetru C. Hoffmann J.A. Latge J.P. Ferrandon D. Roussel A.
TitleThe N-terminal domain of Drosophila Gram-negative binding protein 3 (GNBP3) defines a novel family of fungal pattern recognition receptors.
SourceJ. Biol. Chem. 284:28687-28697(2009).
PubMed ID19692333

4AuthorsKanagawa M. Satoh T. Ikeda A. Adachi Y. Ohno N. Yamaguchi Y.
TitleStructural insights into recognition of triple-helical beta-glucans by an insect fungal receptor.
SourceJ. Biol. Chem. 286:29158-29165(2011).
PubMed ID21697086

5AuthorsDai H. Hiromasa Y. Takahashi D. VanderVelde D. Fabrick J.A. Kanost M.R. Krishnamoorthi R.
TitleAn initial event in the insect innate immune response: structural and biological studies of interactions between beta-1,3-glucan and the N-terminal domain of beta-1,3-glucan recognition protein.
SourceBiochemistry 52:161-170(2013).
PubMed ID23237493


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